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Thin MoO3 films for sensor applications

V. GEORGIEVA1,* , P. STEFANOV2, L. SPASSOV1, Z. RAICHEVA1, M. ATANASSOV1, T. TINCHEVA2, E. MANOLOV1, L. VERGOV1

Affiliation

  1. Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
  2. Institute of General and Inorganic Chemystry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Abstract

This paper reports on the preparation, surface, structural and sorption characterization of as-deposited MoO 3 thin films elaborated by r.f. magnetron sputtering. Characterization of the films was carried out by different techniques. The surface analysis of MoO 3 was performed using X-ray Photoemission Spectroscopy and Scanning Electron Microscopy. X-ray Diffraction was used to study the structure. The refractive index and thickness were determined from ellipsometric measurements. The layers were studied with the objective of developing an NH 3 sensor. The MoO 3 sensitivity to NH3 was estimated using a Quartz Crystal Microbalance (QCM) with thin MoO 3 films sputtered on it. Deposition took place at a deposition rate of 20 nm/min. The sorption property of a QCM with a thin MoO 3 layer was defined as of function of the mass-loading, resulting in a frequency change of the QCM Δf after exposure to different NH 3 concentrations. In our experiments, the NH3 concentrations was changed in the range 50 to 1000 ppm and frequency changes from 96 to 312 Hz were registered. On the basisе of the measured Δf for each concentration, the actual sorbed mass was calculated. The obtained results on the MoO 3 sorption properties can be successfully applied in the development of a NH 3 sensor..

Keywords

MoO 3 thin films, QCM sensor, NH3 gas adsorption.

Submitted at: Nov. 5, 2008
Accepted at: Oct. 3, 2009

Citation

V. GEORGIEVA, P. STEFANOV, L. SPASSOV, Z. RAICHEVA, M. ATANASSOV, T. TINCHEVA, E. MANOLOV, L. VERGOV, Thin MoO3 films for sensor applications, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 10, pp. 1363-1366 (2009)